The conversion from Degree Rankine (°R) to Degree Celsius (°C) is a fundamental process in various scientific and engineering applications. Degree Rankine is a temperature scale used primarily in the United States to measure the temperature of a substance, with absolute zero being 0 °R and the freezing point of water at 491.67 °R. On the other hand, the Celsius scale is widely used globally, with absolute zero at 0 °C and the freezing point of water at 0 °C. To convert °R to °C, the formula °C = (°R - 491.67) × 5/9 is applied. This conversion is essential in fields like thermodynamics, refrigeration, and heating, ventilation, and air conditioning (HVAC), where precise temperature measurements are crucial for designing and operating systems efficiently.